[syzbot] [fs?] KASAN: use-after-free Read in hpfs_get_ea

[syzbot] [fs?] KASAN: use-after-free Read in hpfs_get_ea

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    155a3c003e55 Merge tag 'for-6.16/dm-fixes-2' of git://git...
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=166d6382580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f09d04131ef56b22
dashboard link: https://syzkaller.appspot.com/bug?extid=fa88eb476e42878f2844
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14b20d8c580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16ebe58c580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/8b4489a1d2de/disk-155a3c00.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1c498d4c0c85/vmlinux-155a3c00.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ea8acdf1d890/bzImage-155a3c00.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/e47f2d7541be/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fa88eb476e42878f2844@syzkaller.appspotmail.com

hpfs: filesystem error: warning: spare dnodes used, try chkdsk
hpfs: You really don't want any checks? You are crazy...
hpfs: hpfs_map_sector(): read error
hpfs: code page support is disabled
==================================================================
BUG: KASAN: use-after-free in strcmp+0x6f/0xc0 lib/string.c:283
Read of size 1 at addr ffff8880116728a6 by task syz-executor411/6741

CPU: 1 UID: 0 PID: 6741 Comm: syz-executor411 Not tainted 6.16.0-rc6-syzkaller-00002-g155a3c003e55 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x230 mm/kasan/report.c:480
 kasan_report+0x118/0x150 mm/kasan/report.c:593
 strcmp+0x6f/0xc0 lib/string.c:283
 hpfs_get_ea+0x114/0xdb0 fs/hpfs/ea.c:139
 hpfs_read_inode+0x19d/0x1010 fs/hpfs/inode.c:63
 hpfs_fill_super+0x12bd/0x2070 fs/hpfs/super.c:654
 get_tree_bdev_flags+0x40e/0x4d0 fs/super.c:1681
 vfs_get_tree+0x92/0x2b0 fs/super.c:1804
 do_new_mount+0x24a/0xa40 fs/namespace.c:3902
 do_mount fs/namespace.c:4239 [inline]
 __do_sys_mount fs/namespace.c:4450 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4427
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f718b86112a
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 5e 04 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffee99fcba8 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffee99fcbc0 RCX: 00007f718b86112a
RDX: 0000200000009e80 RSI: 0000200000009ec0 RDI: 00007ffee99fcbc0
RBP: 0000200000009ec0 R08: 00007ffee99fcc00 R09: 0000000000009dfd
R10: 0000000000000041 R11: 0000000000000286 R12: 0000200000009e80
R13: 0000000000000004 R14: 0000000000000003 R15: 00007ffee99fcc00
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11672
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea0001ff38c8 ffffea0001ff3908 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 5213, tgid 5213 (udevd), ts 38150701195, free_ts 195740390996
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704
 prep_new_page mm/page_alloc.c:1712 [inline]
 get_page_from_freelist+0x21d5/0x22b0 mm/page_alloc.c:3669
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419
 folio_alloc_mpol_noprof+0x39/0x70 mm/mempolicy.c:2438
 shmem_alloc_folio mm/shmem.c:1851 [inline]
 shmem_alloc_and_add_folio+0x447/0xf60 mm/shmem.c:1890
 shmem_get_folio_gfp+0x59d/0x1660 mm/shmem.c:2536
 shmem_get_folio mm/shmem.c:2642 [inline]
 shmem_write_begin+0xf7/0x2b0 mm/shmem.c:3292
 generic_perform_write+0x2c7/0x910 mm/filemap.c:4112
 shmem_file_write_iter+0xf8/0x120 mm/shmem.c:3467
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x54b/0xa90 fs/read_write.c:686
 ksys_write+0x145/0x250 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 6740 tgid 6740 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1248 [inline]
 free_unref_folios+0xcd2/0x1570 mm/page_alloc.c:2763
 folios_put_refs+0x559/0x640 mm/swap.c:992
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x49e/0x14b0 mm/shmem.c:1125
 shmem_truncate_range mm/shmem.c:1237 [inline]
 shmem_evict_inode+0x272/0xa70 mm/shmem.c:1365
 evict+0x501/0x9c0 fs/inode.c:810
 __dentry_kill+0x209/0x660 fs/dcache.c:669
 shrink_kill+0xa9/0x2c0 fs/dcache.c:1114
 shrink_dentry_list+0x2e0/0x5e0 fs/dcache.c:1141
 shrink_dcache_parent+0xa1/0x2c0 fs/dcache.c:-1
 do_one_tree+0x23/0xe0 fs/dcache.c:1604
 shrink_dcache_for_umount+0xa0/0x170 fs/dcache.c:1621
 generic_shutdown_super+0x67/0x2c0 fs/super.c:621
 kill_anon_super fs/super.c:1282 [inline]
 kill_litter_super+0x76/0xb0 fs/super.c:1292
 deactivate_locked_super+0xbc/0x130 fs/super.c:474
 cleanup_mnt+0x425/0x4c0 fs/namespace.c:1417
 task_work_run+0x1d4/0x260 kernel/task_work.c:227

Memory state around the buggy address:
 ffff888011672780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888011672800: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888011672880: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                               ^
 ffff888011672900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888011672980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


---
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If the report is already addressed, let syzbot know by replying with:
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If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

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#syz undup

Re: [syzbot] [fs?] KASAN: use-after-free Read in hpfs_get_ea

[syzbot]

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

failed to apply patch:
checking file fs/hpfs/ea.c
patch: **** malformed patch at line 36:   if (ea_indirect(ea))




Tested on:

commit:         6832a931 Merge tag 'net-6.16-rc7' of git://git.kernel...
git tree:       upstream
kernel config:  https://syzkaller.appspot.com/x/.config?x=f09d04131ef56b22
dashboard link: https://syzkaller.appspot.com/bug?extid=fa88eb476e42878f2844
compiler:       
patch:          https://syzkaller.appspot.com/x/patch.diff?x=129db382580000

Re: [syzbot] [fs?] KASAN: use-after-free Read in hpfs_get_ea

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: use-after-free Read in hpfs_get_ea

hpfs: filesystem error: warning: spare dnodes used, try chkdsk
hpfs: You really don't want any checks? You are crazy...
hpfs: hpfs_map_sector(): read error
hpfs: code page support is disabled
==================================================================
BUG: KASAN: use-after-free in hpfs_get_ea+0x1f7/0xca0 fs/hpfs/ea.c:146
Read of size 1 at addr ffff8880719ea8a3 by task syz.0.16/6612

CPU: 0 UID: 0 PID: 6612 Comm: syz.0.16 Not tainted 6.16.0-rc6-syzkaller-00121-g6832a9317eee-dirty #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x230 mm/kasan/report.c:480
 kasan_report+0x118/0x150 mm/kasan/report.c:593
 hpfs_get_ea+0x1f7/0xca0 fs/hpfs/ea.c:146
 hpfs_read_inode+0x19d/0x1010 fs/hpfs/inode.c:63
 hpfs_fill_super+0x12bd/0x2070 fs/hpfs/super.c:654
 get_tree_bdev_flags+0x40e/0x4d0 fs/super.c:1681
 vfs_get_tree+0x8f/0x2b0 fs/super.c:1804
 do_new_mount+0x24a/0xa40 fs/namespace.c:3902
 do_mount fs/namespace.c:4239 [inline]
 __do_sys_mount fs/namespace.c:4450 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4427
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb45e3900ca
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb45f2c9e68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fb45f2c9ef0 RCX: 00007fb45e3900ca
RDX: 0000200000009e80 RSI: 0000200000009ec0 RDI: 00007fb45f2c9eb0
RBP: 0000200000009e80 R08: 00007fb45f2c9ef0 R09: 0000000000000041
R10: 0000000000000041 R11: 0000000000000246 R12: 0000200000009ec0
R13: 00007fb45f2c9eb0 R14: 0000000000009e02 R15: 0000200000009fc0
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x7fdaad200 pfn:0x719ea
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea0001c67988 ffffea0001c61d88 0000000000000000
raw: 00000007fdaad200 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x140dca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO|__GFP_COMP), pid 6566, tgid 6566 (sed), ts 134996856935, free_ts 135030622689
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704
 prep_new_page mm/page_alloc.c:1712 [inline]
 get_page_from_freelist+0x21d5/0x22b0 mm/page_alloc.c:3669
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419
 folio_alloc_mpol_noprof mm/mempolicy.c:2438 [inline]
 vma_alloc_folio_noprof+0xe4/0x200 mm/mempolicy.c:2473
 folio_prealloc+0x30/0x180 mm/memory.c:-1
 alloc_anon_folio mm/memory.c:5014 [inline]
 do_anonymous_page mm/memory.c:5071 [inline]
 do_pte_missing mm/memory.c:4249 [inline]
 handle_pte_fault mm/memory.c:6069 [inline]
 __handle_mm_fault+0x2c88/0x5620 mm/memory.c:6212
 handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6381
 do_user_addr_fault+0xa81/0x1390 arch/x86/mm/fault.c:1336
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
page last free pid 6566 tgid 6566 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1248 [inline]
 free_unref_folios+0xcd2/0x1570 mm/page_alloc.c:2763
 folios_put_refs+0x559/0x640 mm/swap.c:992
 free_pages_and_swap_cache+0x277/0x520 mm/swap_state.c:264
 __tlb_batch_free_encoded_pages mm/mmu_gather.c:136 [inline]
 tlb_batch_pages_flush mm/mmu_gather.c:149 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:397 [inline]
 tlb_flush_mmu+0x3a0/0x680 mm/mmu_gather.c:404
 tlb_finish_mmu+0xc3/0x1d0 mm/mmu_gather.c:497
 exit_mmap+0x44c/0xb50 mm/mmap.c:1297
 __mmput+0x118/0x410 kernel/fork.c:1121
 exit_mm+0x1da/0x2c0 kernel/exit.c:581
 do_exit+0x648/0x22e0 kernel/exit.c:952
 do_group_exit+0x21c/0x2d0 kernel/exit.c:1105
 __do_sys_exit_group kernel/exit.c:1116 [inline]
 __se_sys_exit_group kernel/exit.c:1114 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1114
 x64_sys_call+0x21ba/0x21c0 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff8880719ea780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880719ea800: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880719ea880: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                               ^
 ffff8880719ea900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880719ea980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


Tested on:

commit:         6832a931 Merge tag 'net-6.16-rc7' of git://git.kernel...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=155f38f0580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f09d04131ef56b22
dashboard link: https://syzkaller.appspot.com/bug?extid=fa88eb476e42878f2844
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1644fd8c580000

Re: [syzbot] [fs?] KASAN: use-after-free Read in hpfs_get_ea

[syzbot]

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

failed to apply patch:
checking file fs/hpfs/ea.c
Hunk #1 succeeded at 135 with fuzz 1.
patch: **** malformed patch at line 61: + }




Tested on:

commit:         414aaef1 Merge tag 'riscv-for-linus-6.16-rc7' of git:/..
git tree:       upstream
kernel config:  https://syzkaller.appspot.com/x/.config?x=f09d04131ef56b22
dashboard link: https://syzkaller.appspot.com/bug?extid=fa88eb476e42878f2844
compiler:       
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1165038c580000

Re: [syzbot] [fs?] KASAN: use-after-free Read in hpfs_get_ea

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: use-after-free Read in hpfs_get_ea

hpfs: filesystem error: improperly stopped
hpfs: filesystem error: warning: spare dnodes used, try chkdsk
hpfs: You really don't want any checks? You are crazy...
hpfs: hpfs_map_sector(): read error
hpfs: code page support is disabled
==================================================================
BUG: KASAN: use-after-free in hpfs_get_ea+0x1e4/0xcb0 fs/hpfs/ea.c:140
Read of size 1 at addr ffff888066cc98a3 by task syz.0.17/6635

CPU: 0 UID: 0 PID: 6635 Comm: syz.0.17 Not tainted 6.16.0-rc6-syzkaller-00253-g4871b7cb27f4-dirty #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x230 mm/kasan/report.c:480
 kasan_report+0x118/0x150 mm/kasan/report.c:593
 hpfs_get_ea+0x1e4/0xcb0 fs/hpfs/ea.c:140
 hpfs_read_inode+0x19d/0x1010 fs/hpfs/inode.c:63
 hpfs_fill_super+0x12bd/0x2070 fs/hpfs/super.c:654
 get_tree_bdev_flags+0x40e/0x4d0 fs/super.c:1681
 vfs_get_tree+0x8f/0x2b0 fs/super.c:1804
 do_new_mount+0x24a/0xa40 fs/namespace.c:3902
 do_mount fs/namespace.c:4239 [inline]
 __do_sys_mount fs/namespace.c:4450 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4427
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f962d1900ca
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f962df7fe68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f962df7fef0 RCX: 00007f962d1900ca
RDX: 0000200000009e80 RSI: 0000200000009ec0 RDI: 00007f962df7feb0
RBP: 0000200000009e80 R08: 00007f962df7fef0 R09: 0000000000000041
R10: 0000000000000041 R11: 0000000000000246 R12: 0000200000009ec0
R13: 00007f962df7feb0 R14: 0000000000009e02 R15: 0000200000009fc0
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x3 pfn:0x66cc9
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea0001a32348 ffffea0001c6d988 0000000000000000
raw: 0000000000000003 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 6622, tgid 6622 (sed), ts 137283206252, free_ts 137322824885
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704
 prep_new_page mm/page_alloc.c:1712 [inline]
 get_page_from_freelist+0x21d5/0x22b0 mm/page_alloc.c:3669
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419
 folio_alloc_mpol_noprof mm/mempolicy.c:2438 [inline]
 vma_alloc_folio_noprof+0xe4/0x200 mm/mempolicy.c:2473
 folio_prealloc+0x30/0x180 mm/memory.c:-1
 do_cow_fault mm/memory.c:5614 [inline]
 do_fault mm/memory.c:5726 [inline]
 do_pte_missing mm/memory.c:4251 [inline]
 handle_pte_fault mm/memory.c:6069 [inline]
 __handle_mm_fault+0x183f/0x5620 mm/memory.c:6212
 handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6381
 do_user_addr_fault+0x764/0x1390 arch/x86/mm/fault.c:1387
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
page last free pid 6622 tgid 6622 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1248 [inline]
 free_unref_folios+0xcd2/0x1570 mm/page_alloc.c:2763
 folios_put_refs+0x559/0x640 mm/swap.c:992
 free_pages_and_swap_cache+0x4be/0x520 mm/swap_state.c:267
 __tlb_batch_free_encoded_pages mm/mmu_gather.c:136 [inline]
 tlb_batch_pages_flush mm/mmu_gather.c:149 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:397 [inline]
 tlb_flush_mmu+0x3a0/0x680 mm/mmu_gather.c:404
 tlb_finish_mmu+0xc3/0x1d0 mm/mmu_gather.c:497
 exit_mmap+0x44c/0xb50 mm/mmap.c:1297
 __mmput+0x118/0x410 kernel/fork.c:1121
 exit_mm+0x1da/0x2c0 kernel/exit.c:581
 do_exit+0x648/0x22e0 kernel/exit.c:952
 do_group_exit+0x21c/0x2d0 kernel/exit.c:1105
 __do_sys_exit_group kernel/exit.c:1116 [inline]
 __se_sys_exit_group kernel/exit.c:1114 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1114
 x64_sys_call+0x21ba/0x21c0 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888066cc9780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888066cc9800: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888066cc9880: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                               ^
 ffff888066cc9900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888066cc9980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


Tested on:

commit:         4871b7cb Merge tag 'v6.16-rc6-smb3-client-fixes' of gi..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11773d8c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f09d04131ef56b22
dashboard link: https://syzkaller.appspot.com/bug?extid=fa88eb476e42878f2844
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
patch:          https://syzkaller.appspot.com/x/patch.diff?x=13473d8c580000

Re: [syzbot] [fs?] KASAN: use-after-free Read in hpfs_get_ea

[syzbot]

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

fs/hpfs/ea.c:139:54: error: no member named 'ea_off' in 'struct fnode'
fs/hpfs/ea.c:139:70: error: no member named 'ea_size' in 'struct fnode'
fs/hpfs/ea.c:140:41: error: no member named 'name_len' in 'struct extended_attribute'; did you mean 'namelen'?
fs/hpfs/ea.c:143:57: error: no member named 'ea_off' in 'struct fnode'
fs/hpfs/ea.c:143:73: error: no member named 'ea_size' in 'struct fnode'
fs/hpfs/ea.c:146:17: error: no member named 'name_len' in 'struct extended_attribute'; did you mean 'namelen'?
fs/hpfs/ea.c:149:56: error: no member named 'ea_off' in 'struct fnode'
fs/hpfs/ea.c:149:72: error: no member named 'ea_size' in 'struct fnode'
fs/hpfs/ea.c:152:11: error: no member named 'name_len' in 'struct extended_attribute'
fs/hpfs/ea.c:152:23: error: use of undeclared identifier 'aname'
fs/hpfs/ea.c:152:55: error: use of undeclared identifier 'aname'
fs/hpfs/ea.c:153:12: error: no member named 'type' in 'struct extended_attribute'
fs/hpfs/ea.c:154:27: error: no member named 'size' in 'struct extended_attribute'
fs/hpfs/ea.c:154:6: error: use of undeclared identifier 'buffer'
fs/hpfs/ea.c:155:11: error: use of undeclared identifier 'buffer'
fs/hpfs/ea.c:156:13: error: incompatible integer to pointer conversion returning 'int' from a function with result type 'char *' [-Wint-conversion]
fs/hpfs/ea.c:157:50: error: no member named 'size' in 'struct extended_attribute'


Tested on:

commit:         f4a40a42 Merge tag 'efi-fixes-for-v6.16-2' of git://gi..
git tree:       upstream
kernel config:  https://syzkaller.appspot.com/x/.config?x=f09d04131ef56b22
dashboard link: https://syzkaller.appspot.com/bug?extid=fa88eb476e42878f2844
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
patch:          https://syzkaller.appspot.com/x/patch.diff?x=13b084f0580000

Re: [syzbot] [fs?] KASAN: use-after-free Read in hpfs_get_ea

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: use-after-free Read in hpfs_get_ea

hpfs: filesystem error: invalid number of hotfixes: 2066844986, used: 2066844985; already mounted read-only
hpfs: filesystem error: improperly stopped
hpfs: filesystem error: warning: spare dnodes used, try chkdsk
hpfs: You really don't want any checks? You are crazy...
hpfs: hpfs_map_sector(): read error
hpfs: code page support is disabled
==================================================================
BUG: KASAN: use-after-free in hpfs_get_ea+0x1ee/0xc90 fs/hpfs/ea.c:144
Read of size 1 at addr ffff88806051d8a3 by task syz.0.16/6564

CPU: 1 UID: 0 PID: 6564 Comm: syz.0.16 Not tainted 6.16.0-rc6-syzkaller-00281-gf4a40a4282f4-dirty #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x230 mm/kasan/report.c:480
 kasan_report+0x118/0x150 mm/kasan/report.c:593
 hpfs_get_ea+0x1ee/0xc90 fs/hpfs/ea.c:144
 hpfs_read_inode+0x19d/0x1010 fs/hpfs/inode.c:63
 hpfs_fill_super+0x12bd/0x2070 fs/hpfs/super.c:654
 get_tree_bdev_flags+0x40e/0x4d0 fs/super.c:1681
 vfs_get_tree+0x8f/0x2b0 fs/super.c:1804
 do_new_mount+0x24a/0xa40 fs/namespace.c:3902
 do_mount fs/namespace.c:4239 [inline]
 __do_sys_mount fs/namespace.c:4450 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4427
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2b0bb900ca
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2b0ca8de68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f2b0ca8def0 RCX: 00007f2b0bb900ca
RDX: 0000200000009e80 RSI: 0000200000009ec0 RDI: 00007f2b0ca8deb0
RBP: 0000200000009e80 R08: 00007f2b0ca8def0 R09: 0000000000000041
R10: 0000000000000041 R11: 0000000000000246 R12: 0000200000009ec0
R13: 00007f2b0ca8deb0 R14: 0000000000009e02 R15: 0000200000009fc0
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x2 pfn:0x6051d
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea00017f91c8 ffffea0001814508 0000000000000000
raw: 0000000000000002 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 6526, tgid 6526 (sed), ts 155457290558, free_ts 155502026680
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704
 prep_new_page mm/page_alloc.c:1712 [inline]
 get_page_from_freelist+0x21d5/0x22b0 mm/page_alloc.c:3669
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419
 folio_alloc_mpol_noprof mm/mempolicy.c:2438 [inline]
 vma_alloc_folio_noprof+0xe4/0x200 mm/mempolicy.c:2473
 folio_prealloc+0x30/0x180 mm/memory.c:-1
 wp_page_copy mm/memory.c:3569 [inline]
 do_wp_page+0x1231/0x5800 mm/memory.c:4030
 handle_pte_fault mm/memory.c:6085 [inline]
 __handle_mm_fault+0x1144/0x5620 mm/memory.c:6212
 handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6381
 do_user_addr_fault+0xa81/0x1390 arch/x86/mm/fault.c:1336
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
page last free pid 6526 tgid 6526 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1248 [inline]
 free_unref_folios+0xcd2/0x1570 mm/page_alloc.c:2763
 folios_put_refs+0x559/0x640 mm/swap.c:992
 free_pages_and_swap_cache+0x4be/0x520 mm/swap_state.c:267
 __tlb_batch_free_encoded_pages mm/mmu_gather.c:136 [inline]
 tlb_batch_pages_flush mm/mmu_gather.c:149 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:397 [inline]
 tlb_flush_mmu+0x3a0/0x680 mm/mmu_gather.c:404
 tlb_finish_mmu+0xc3/0x1d0 mm/mmu_gather.c:497
 exit_mmap+0x44c/0xb50 mm/mmap.c:1297
 __mmput+0x118/0x410 kernel/fork.c:1121
 exit_mm+0x1da/0x2c0 kernel/exit.c:581
 do_exit+0x648/0x22e0 kernel/exit.c:952
 do_group_exit+0x21c/0x2d0 kernel/exit.c:1105
 __do_sys_exit_group kernel/exit.c:1116 [inline]
 __se_sys_exit_group kernel/exit.c:1114 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1114
 x64_sys_call+0x21ba/0x21c0 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88806051d780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88806051d800: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88806051d880: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                               ^
 ffff88806051d900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88806051d980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


Tested on:

commit:         f4a40a42 Merge tag 'efi-fixes-for-v6.16-2' of git://gi..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=116f8b82580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f09d04131ef56b22
dashboard link: https://syzkaller.appspot.com/bug?extid=fa88eb476e42878f2844
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
patch:          https://syzkaller.appspot.com/x/patch.diff?x=16e5b7d4580000

Re: [syzbot] [fs?] KASAN: use-after-free Read in hpfs_get_ea

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+fa88eb476e42878f2844@syzkaller.appspotmail.com
Tested-by: syzbot+fa88eb476e42878f2844@syzkaller.appspotmail.com

Tested on:

commit:         f4a40a42 Merge tag 'efi-fixes-for-v6.16-2' of git://gi..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12314b82580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f09d04131ef56b22
dashboard link: https://syzkaller.appspot.com/bug?extid=fa88eb476e42878f2844
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
patch:          https://syzkaller.appspot.com/x/patch.diff?x=17c0538c580000

Note: testing is done by a robot and is best-effort only.

Re: [syzbot] [fs?] KASAN: use-after-free Read in hpfs_get_ea

[Tetsuo Handa]

#syz test

diff --git a/fs/hpfs/Kconfig b/fs/hpfs/Kconfig
index ac1e9318e65a..d3dfbe76be8a 100644
--- a/fs/hpfs/Kconfig
+++ b/fs/hpfs/Kconfig
@@ -15,3 +15,14 @@ config HPFS_FS
 
 	  To compile this file system support as a module, choose M here: the
 	  module will be called hpfs.  If unsure, say N.
+
+config HPFS_FS_ALLOW_NO_ERROR_CHECK_MODE
+	bool "Allow no-error-check mode for maximum speed"
+	depends on HPFS_FS
+	default n
+	help
+	  This option enables check=none mount option. If check=none is
+	  specified, users can expect maximum speed at the cost of minimum
+	  robustness. Sane users should not specify check=none option, for e.g.
+	  use-after-free bug will happen when the filesystem is corrupted or
+	  crafted.
diff --git a/fs/hpfs/super.c b/fs/hpfs/super.c
index 42b779b4d87f..558093b2beab 100644
--- a/fs/hpfs/super.c
+++ b/fs/hpfs/super.c
@@ -285,7 +285,9 @@ static const struct constant_table hpfs_param_case[] = {
 };
 
 static const struct constant_table hpfs_param_check[] = {
+#ifdef CONFIG_HPFS_FS_ALLOW_NO_ERROR_CHECK_MODE
 	{"none",	0},
+#endif
 	{"normal",	1},
 	{"strict",	2},
 	{}

Re: [syzbot] [fs?] KASAN: use-after-free Read in hpfs_get_ea

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+fa88eb476e42878f2844@syzkaller.appspotmail.com
Tested-by: syzbot+fa88eb476e42878f2844@syzkaller.appspotmail.com

Tested on:

commit:         3a866087 Linux 6.18-rc1
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14d2bb34580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=858c39e0498e4460
dashboard link: https://syzkaller.appspot.com/bug?extid=fa88eb476e42878f2844
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=12cb467c580000

Note: testing is done by a robot and is best-effort only.